My invention pertains to an advance train line register control arrangement for a train speed regulation system. More specifically, the invention pertains to an advance train line register which provides analog signals to an advance train line encoder to control train propulsion means to increase or decrease train speed in discrete steps and which also provides clock pulses for actuating an associated propulsion train line encoder.
The prior art technology in rapid transit operation uses a parallel-series tractive effort control system. In this arrangement, the four propulsion motors and associated control resistors on each car of a train are initially connected in series across the power source. To increase power and therefore speed, the control resistors are cut out in steps, and then the motor field energy is weakened. Following this, the motors are switched to a parallel-series combination, normally with two parallel pairs of motors connected in series across the power source with the same control resistors. Once again, each resistor is again cut out in steps, and then the motor fields are weakened, all of this increasing the speed of the train. Obviously, a reverse order of this stepping action occurs when train speed is being decreased gradually, although the complete shut-off of the propulsion motors is always possible in an emergency. Originally, and still existing in some older rapid transit systems, the motorman or train operator manually controls the train speed from a single position in the lead car using switching contactor apparatus. Each car of the train is controlled simultaneously to the same propulsion condition through train line wires running the length of the train and automatically connected from car to car when the cars are coupled together to form the train. Subsequently, a variable control of propulsion effort was developed in which variations of the propulsion level exist throughout the train. In other words, the level of propulsion effort on each car is controlled semi-independently of the level existing on other cars of the train. For example, the propulsion motors on every other car may be cut out in order to reduce the total tractive effort. However, an even more sophisticated variable control arrangement is desirable for automatic train operation. For example, it is desirable that each car individually advance to the next higher power state than that called for by the propulsion train line control, with this propulsion advance stepped car by car from the leading car to the rear of the train. Such a car by car advancing of the propulsion or tractive effort requires an advance train line channel, separate and distinct from the regular propulsion train lines. This separate, advance train line channel must be controlled by an encoder arrangement to establish a particular step level in accordance with the number of cars of the train which are to be advanced or retarded from the existing propulsion or tractive effort base established by the regular propulsion train line apparatus. The advance train line encoder must also signal the propulsion train line apparatus when the maximum advance has been reached, that is, when all the cars are at the same advance level, so that the base propulsion level then may be shifted and the advance procedure restarted. This car by car advance control must also be capable of reducing the propulsion effort from the previously selected level to a lower tractive effort car by car and then causing the propulsion train line apparatus to reduce its base selection to that lower total level.
Accordingly,, an object of my invention is an advance train line control apparatus which varies the train propulsion level car by car throughout a train.
Another object of the invention is an advance train line control arrangement responsive to propulsion demand signals to advance the propulsion power level car by car in a rapid transit train and to activate propulsion train line apparatus when the maximum advance to the next higher propulsion level is achieved to register the increase to that level.
A further object of my invention is advance train line apparatus for a rapid transit train to advance or retard the propulsion level of the train in one car steps above or below, respectively, the base propulsion level established by the regular propulsion train line apparatus.
Still another object of the invention is advance train line apparatus to advance or retard the propulsion level of a rapid transit train by one predetermined step, sequentially car by car and to activate the propulsion train line encoder to the next higher or lower propulsion level, respectively, when the maximum variation in either direction has been reached by the advance train line apparatus.
Also an object of the invention is advance train line control apparatus for a rapid transit train which, upon receipt of a velocity brake error signal, advances or retards the propulsion level of the train, in accordance with the direction of the error, in single car steps from the existing base level established by a propulsion train line signal, further activating the propulsion train line apparatus to the next higher or lower base level when the propulsion effort of all cars has been varied one step.
Yet another object of the invention is advance train line apparatus for a train speed regulation system which counts clock pulses representing a velocity error between desired and actual speeds of the train, adding or subtracting each pulse in accord with the state of a direction signal representing the under or over speed status of the error, converts the digital pulse count into a stepped analog signal to drive an advance train line channel apparatus to vary the propulsion level car by car, and generates a clock pulse at the completion of each full cycle of step varying of the train propulsion effort, either increase or decrease, to step an associated propulsion train line encoder to a corresponding base propulsion level.
Other objects, advantages, and features of my invention will become apparent from the following specification when taken in connection with the accompaning drawings and appended claims.